Apparatuses for screen testing an optical fiber and methods for using the same

ABSTRACT

In one embodiment, an apparatus for screen testing an optical fiber includes a fiber conveyance pathway, a capstan having an outer circumference and a fiber contact region extending around the outer circumference, the fiber contact region having a durometer hardness of less than or equal to about 40 Shore A, where the capstan is positioned adjacent to the fiber conveyance pathway such that when the optical fiber is directed over the fiber conveyance pathway, the optical fiber engages with the fiber contact region, and a pinch belt positioned adjacent to the fiber conveyance pathway such that the fiber conveyance pathway extends between the pinch belt and the fiber contact region, where the pinch belt is engagable with the fiber contact region such that, when the optical fiber is directed over the fiber conveyance pathway, the optical fiber is impinged between the pinch belt and the fiber contact region.

This application is a divisional of and claims the benefit of priorityunder 35 U.S.C. § 20 of U.S. application Ser. No. 14/696,890 filed onApr. 27, 2015, which claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 61/990793 filed on May 9,2014, the content of which is relied upon and incorporated herein byreference in its entirety.

BACKGROUND

Field

The present specification generally relates to screen testing fiber and,more specifically to apparatuses and methods for screen testing opticalfiber.

Technical Background

Capstan assemblies used in the manufacture of optical fiber aretypically used to draw the optical fiber from glass blanks that aremounted within draw towers, and/or for proof testing of the opticalfiber, also known as fiber screening or screen testing. For consistency,the term screen testing will be used herein.

Capstan assemblies may include a capstan and a pinch belt between whichthe optical fiber is positioned. As the capstan is rotated, the frictiongenerated between the capstan, the optical fiber, and the pinch beltpulls or draws the optical fiber from the associated glass blank througha series of related operations such as coating and sizing steps. Whenused in tandem, a pair of capstans can also be used to test the proofstrength of the optical fiber by placing a tensile stress thereon.

During the screen test, the capstan and the pinch belt impose shear andcompressive stresses on a coating of the optical fiber, and may causedamage to the coating, resulting in the optical fiber being discarded,thereby increasing manufacturing costs and reducing production yields.

Accordingly, a need exists for alternative screen testing apparatusesfor limiting the effect of shear and compressive stresses imposed on thecoating of an optical fiber.

SUMMARY

According to one embodiment, an apparatus for screen testing an opticalfiber includes a fiber conveyance pathway, a capstan having an outercircumference and a fiber contact region extending around the outercircumference, the fiber contact region having a durometer hardness ofless than or equal to about 40 Shore A, where the capstan is positionedadjacent to the fiber conveyance pathway such that when the opticalfiber is directed over the fiber conveyance pathway, the optical fiberengages with the fiber contact region of the capstan, and a pinch beltpositioned adjacent to the fiber conveyance pathway such that the fiberconveyance pathway extends between at least a portion of the pinch beltand the fiber contact region of the capstan, wherein the pinch belt isengagable with the fiber contact region of the capstan such that, whenthe optical fiber is directed over the fiber conveyance pathway, theoptical fiber is impinged between the pinch belt and the fiber contactregion of the capstan.

In another embodiment, an apparatus for screen testing an optical fiberincluding a fiber conveyance pathway, a capstan having an outercircumference and a fiber contact region extending around the outercircumference, the fiber contact region having a durometer hardness ofless than or equal to about 40 Shore A, the fiber contact regionincluding an inner layer of resilient material positioned on the outercircumference of the capstan, an outer layer of wear-resistant materialpositioned over the inner layer of resilient material, the outer layerof wear-resistant material having a durometer hardness of less than orequal to about 90 Shore A, and a pinch belt positioned adjacent to thefiber conveyance pathway such that the fiber conveyance pathway extendsbetween at least a portion of the pinch belt and the fiber contactregion of the capstan, where the pinch belt is engagable with the fibercontact region of the capstan such that, when the optical fiber directedover the fiber conveyance pathway, the optical fiber is impinged betweenthe pinch belt and the fiber contact region of the capstan.

In yet another embodiment, a method for screen testing an optical fiberincludes directing an optical fiber on a fiber conveyance pathway,directing the optical fiber around a capstan, the capstan having anouter circumference and a fiber contact region extending around theouter circumference, the fiber contact region including an inner layerof resilient material positioned on the outer circumference of thecapstan, an outer layer of wear-resistant material positioned over theinner layer of resilient material, the outer layer of wear-resistantmaterial having a durometer hardness of less than or equal to 90 ShoreA, wherein the fiber contact region has a durometer hardness of lessthan or equal to 40 Shore A, and impinging the optical fiber between apinch belt positioned adjacent to the fiber conveyance pathway and thefiber contact region of the capstan, wherein the fiber contact regionelastically deforms and the optical fiber is depressed into the fibercontact region of the capstan.

Additional features and advantages of the apparatuses and methods forscreen testing an optical fiber described herein will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the embodiments described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description describe various embodiments and areintended to provide an overview or framework for understanding thenature and character of the claimed subject matter. The accompanyingdrawings are included to provide a further understanding of the variousembodiments, and are incorporated into and constitute a part of thisspecification. The drawings illustrate the various embodiments describedherein, and together with the description serve to explain theprinciples and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a perspective view of an apparatus forscreen testing an optical fiber including a capstan and a pinch beltaccording to one or more embodiments shown or described herein;

FIG. 2 schematically depicts a capstan and pinch belt according to oneor more embodiments shown or described herein;

FIG. 3 schematically depicts a cross-sectional view of a coated opticalfiber under compressive stress;

FIG. 4 schematically depicts a cross-sectional view of a coated opticalfiber under shear stress;

FIG. 5A schematically depicts a perspective cross-sectional view of acapstan according to one or more embodiments shown or described herein;

FIG. 5B schematically depicts a front-view cross section of a capstanaccording to one or more embodiments shown or described herein;

FIG. 5C schematically depicts an enlarged view of a portion of across-section of a capstan according to one or more embodiments shown ordescribed herein;

FIG. 6A schematically depicts a perspective cross-sectional view of acapstan according to one or more embodiments shown or described herein;

FIG. 6B schematically depicts a front-view cross section of a capstanaccording to one or more embodiments shown or described herein;

FIG. 6C schematically depicts an enlarged view of a portion of across-section of a capstan according to one or more embodiments shown ordescribed herein;

FIG. 7A schematically depicts a perspective cross-sectional view of acapstan according to one or more embodiments shown or described herein;

FIG. 7B schematically depicts a front-view cross section of a capstanaccording to one or more embodiments shown or described herein;

FIG. 7C schematically depicts an enlarged view of a portion of across-section of a capstan according to one or more embodiments shown ordescribed herein;

FIG. 8A schematically depicts a perspective cross-sectional view of acapstan according to one or more embodiments shown or described herein;

FIG. 8B schematically depicts a front-view cross section of a capstanaccording to one or more embodiments shown or described herein;

FIG. 8C schematically depicts an enlarged view of a portion of across-section of a capstan according to one or more embodiments shown ordescribed herein;

FIG. 9A schematically depicts a perspective cross-sectional view of acapstan according to one or more embodiments shown or described herein;

FIG. 9B schematically depicts a front-view cross section of a capstanaccording to one or more embodiments shown or described herein;

FIG. 9C schematically depicts a section-view of a capstan according toone or more embodiments shown or described herein;

FIG. 9D schematically depicts an enlarged view of a portion of across-section of a capstan according to one or more embodiments shown ordescribed herein;

FIG. 10A schematically depicts a perspective cross-sectional view of acapstan according to one or more embodiments shown or described herein;

FIG. 10B schematically depicts a front-view cross section of a capstanaccording to one or more embodiments shown or described herein;

FIG. 10C schematically depicts a section-view of a capstan according toone or more embodiments shown or described herein;

FIG. 10D schematically depicts an enlarged view of a portion of across-section of a capstan according to one or more embodiments shown ordescribed herein;

FIG. 11A schematically depicts a perspective cross-sectional view of acapstan according to one or more embodiments shown or described herein;

FIG. 11B schematically depicts a front-view cross section of a capstanaccording to one or more embodiments shown or described herein;

FIG. 11C schematically depicts an enlarged view of a portion of across-section of a capstan according to one or more embodiments shown ordescribed herein;

FIG. 12 schematically depicts a perspective cross-sectional view of acapstan according to one or more embodiments shown or described herein;

FIG. 13 schematically depicts a cross-section view of a coated opticalfiber directed over a fiber conveyance pathway under compressive stressaccording to one or more embodiments shown or described herein; and

FIG. 14 schematically depicts a cross-section view of a coated opticalfiber directed over a fiber conveyance pathway under shear stressaccording to one or more embodiments shown or described herein.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the apparatusesand methods for screen testing an optical fiber described herein,examples of which are illustrated in the accompanying drawings. Wheneverpossible, the same reference numerals will be used throughout thedrawings to refer to the same or like parts. In one embodiment, anapparatus for screen testing an optical fiber includes a fiberconveyance pathway, a capstan having an outer circumference and a fibercontact region extending around the outer circumference, the fibercontact region having a durometer hardness of less than or equal toabout 40 Shore A, where the capstan is positioned adjacent to the fiberconveyance pathway such that when the optical fiber is directed over thefiber conveyance pathway, the optical fiber engages with the fibercontact region of the capstan, and a pinch belt positioned adjacent tothe fiber conveyance pathway such that the fiber conveyance pathwayextends between at least a portion of the pinch belt and the fibercontact region of the capstan, wherein the pinch belt is engagable withthe fiber contact region of the capstan such that, when the opticalfiber is directed over the fiber conveyance pathway, the optical fiberis impinged between the pinch belt and the fiber contact region of thecapstan. Methods and apparatuses for screen testing optical fiber willbe described in more detail herein with specific reference to theappended drawings.

Optical fibers may be formed by drawing a thin glass fiber from a glassblank or “preform.” After the optical fiber is drawn from the glassblank, one or more coatings may be applied to the glass fiber to protectthe glass and preserve the structural integrity of the optical fiber. Toform optical fiber having an extended length, a plurality of opticalfibers may be consecutively spliced together. To splice together a pairof optical fibers, the one or more coatings are stripped from the glassfibers near the ends that are to be joined together. The ends of the twoglass fibers are joined together, and a re-coat coating may be appliedto the optical fiber to replace the stripped coatings.

The re-coat coating applied to replace the stripped coatings may have adifferent compressive and shear modulus than the one or more coatings ofthe original optical fibers. In particular, the re-coat coating may havea higher compressive modulus and a higher shear modulus than the one ormore coatings on the original optical fibers. Because the re-coatcoating has a higher compressive modulus and shear modulus than the oneor more coatings of the optical fibers, the re-coat coating may exhibitless elastic deformation under compressive forces and shear forcesimposed by the capstan and pinch belt. Because the re-coat coatingdeforms less than the one or more coatings of the original opticalfibers under the compressive and shear forces imposed by the capstan andpinch belt, stress may be placed on the optical fiber at the interfacebetween the re-coat coating and the one or more coatings of the originaloptical fibers. The stress placed on the optical fiber may lead tocohesive failure at the interface between the re-coat coating and theone or more coatings of the optical fiber. The stress placed on theoptical fiber may also lead to adhesive failure between the one or morecoatings and the glass fiber. Additionally, the stress placed on theoptical fiber may damage an outer surface of the one or more coatings.Accordingly, the stress placed on the optical fiber may damage thecoatings of the optical fiber, leading to optical fiber being discarded,increasing manufacturing costs.

The apparatuses and methods described herein reduce the compressive andshear stress imposed on an optical fiber directed between at least onecapstan and at least one pinch belt during a screen test of the opticalfiber. Reducing the compressive and shear stress imposed on an opticalfiber during a screen test of the optical fiber may reduce thelikelihood of cohesive failure of the coatings of the optical fiber.

Referring to FIG. 1, one embodiment of a screen testing apparatus 100for screen testing an optical fiber is schematically depicted. Thescreen testing apparatus 100 generally includes a fiber conveyancepathway 101 that extends through the screen testing apparatus 100. Thefiber conveyance pathway 101 of the screen testing apparatus 100 definesa pathway over which an optical fiber is directed during the screentest. The screen testing apparatus 100 generally includes at least afirst capstan 102 positioned adjacent to a fiber conveyance pathway 101and at least a first pinch belt 103 positioned adjacent to the fiberconveyance pathway 101 opposite the first capstan 102. The first capstan102 and the first pinch belt 103 are positioned so that the fiberconveyance pathway 101 is positioned between the first capstan 102 andthe first pinch belt 103. As an optical fiber 104 is directed over thefiber conveyance pathway 101, the first pinch belt 103 impinges theoptical fiber 104 between the first pinch belt 103 and the first capstan102.

The first capstan 102 has a first diameter DIA1, and an outercircumference 105. The outer circumference 105 of the first capstan 102is positioned adjacent to the fiber conveyance pathway 101 so that theoptical fiber 104 directed over the fiber conveyance pathway 101 engagesthe outer circumference 105 of the first capstan 102.

The screen testing apparatus 100 may optionally include a second capstan106 positioned adjacent to the fiber conveyance pathway 101 and a secondpinch belt 107 positioned adjacent to the fiber conveyance pathway 101.Similar to the first capstan 102 and the first pinch belt 103, thesecond capstan 106 and the second pinch belt 107 may be positioned sothat the fiber conveyance pathway 101 is positioned between the secondcapstan 106 and the second pinch belt 107. As the optical fiber 104 isdirected over the fiber conveyance pathway 101, the second pinch belt107 impinges the optical fiber 104 between the second pinch belt 107 andthe second capstan 106.

The second capstan 106 may have a second diameter DIA2, and an outercircumference 108. The outer circumference 108 of the second capstan 106is positioned adjacent to the fiber conveyance pathway 101 so that anoptical fiber 104 directed over the fiber conveyance pathway 101 engagesthe outer circumference 108 of the second capstan 106.

The screen testing apparatus 100 may optionally include a load cell 109and a pulley 110 positioned adjacent to the fiber conveyance pathway101. The load cell 109 and the pulley 110 are positioned adjacent to thefiber conveyance pathway 101 between the first capstan 102 and thesecond capstan 106. The pulley 110 may be positioned adjacent to thefiber conveyance pathway 101 so that the pulley contacts the opticalfiber 104 directed over the fiber conveyance pathway 101. The load cell109 may be coupled to the pulley 110 so that the load cell detects atension in the optical fiber 104 through the contact between the opticalfiber 104 and the pulley 110.

To rotate the first capstan 102 and the second capstan 106, the firstcapstan 102 may be connected to a first driveshaft (not depicted) andthe second capstan 106 may be connected to a second driveshaft (notdepicted) that is driven independent of the first driveshaft. The firstdriveshaft and the second driveshaft may be driven by power sourceswhich may include without limitation, electric motors, pneumaticallydriven spindles, and the like.

The first capstan 102 and the second capstan 106 apply a tensile stresson the optical fiber 104 directed over the fiber conveyance pathway 101.To apply a tensile stress on the optical fiber 104, the first capstan102 and the second capstan 106 may be rotated at different rotationalspeeds. More specifically, the second capstan 106 may be rotated at ahigher rotational speed than the first capstan 102. As a result of thehigher rotational speed of the second capstan 106, a portion of theoptical fiber 104 between the first capstan 102 and the second capstan106 on the fiber conveyance pathway 101 will be under tension.

Alternatively, to apply a tensile stress to the optical fiber, thediameter DIA2 of the second capstan 106 may be selected to be largerthan the diameter DIA1 of the first capstan 102. When the rotationalspeed of the second capstan 106 is the same or higher than therotational speed of the first capstan 102, and the diameter DIA2 of thesecond capstan 106 is greater than the diameter DIA1 of the firstcapstan 102, a linear speed of the outer circumference 108 of the secondcapstan 106 will be higher than a linear speed of the outercircumference 105 of the first capstan 102. As a result of the higherlinear speed of the outer circumference 108 of the second capstan 106,the portion of the optical fiber 104 between the first capstan 102 andthe second capstan 106 on the fiber conveyance pathway 101 will be undertension.

Referring now to FIGS. 1 and 2, to isolate the tension applied to theoptical fiber 104 by the first capstan 102 and the second capstan 106,the first pinch belt 103 impinges the optical fiber 104 between thefirst pinch belt 103 and the first capstan 102. In embodiments, thefirst pinch belt 103 may include a first belt 111 and a plurality ofidler pulleys 112 that are positioned adjacent to the fiber conveyancepathway 101. The first belt 111 is positioned around the plurality ofidler pulleys 112 so that the first belt 111 impinges the optical fiber104 directed over the fiber conveyance pathway 101 between the firstbelt 111 and the first capstan 102. Accordingly, the first pinch belt103 applies a compressive force to the optical fiber 104 between thefirst pinch belt 103 and the first capstan 102 to isolate the tensionapplied to the optical fiber 104 between the first capstan 102 and thesecond capstan 106. In embodiments, the position of the plurality ofidler pulleys 112 may be adjustable, such that a tension in the firstbelt 111 and, accordingly, the compressive force applied to the opticalfiber 104, may be adjusted. To adjust the position of the idler pulleys112, the idler pulleys may be coupled to the screen testing apparatus byactuators, such as pneumatic devices, electric motors, and the like.While reference has been made hereinabove to the configuration of thefirst pinch belt 103 and the first capstan 102, it should be understoodthat the second pinch belt 107 and the second capstan 106 may likewiseinclude a plurality of adjustable idler pulleys 112 to isolate thetension in the optical fiber 104 between the first capstan 102 and thesecond capstan 106.

Referring to FIG. 3, a cross-section of an optical fiber 104 is depictedunder compressive force 127, such as the compressive force applied tothe optical fiber 104 by the first pinch belt 103 and the first capstan102. In particular, FIG. 3 depicts the compressive force 127 applied tothe optical fiber 104 by the first pinch belt 103 and the first capstan102, as the optical fiber 104 is impinged between the first pinch belt103 and the outer circumference 105 of the first capstan 102. Aconveyance direction 128 of the fiber conveyance pathway 101 may extendin a direction generally tangential to the outer circumference 105 ofthe first capstan 102 (i.e., in the +/− Y direction in the coordinateaxis depicted on FIG. 3). The compressive force 127 may be generallyapplied in a direction perpendicular to the conveyance direction 128(i.e., in the +/− X direction in the coordinate axis depicted on FIG.3).

The optical fiber 104 may include a glass fiber 113, a primary coating114, a secondary coating 115, and a re-coat coating 116. The primarycoating 114 may be positioned over the glass fiber 113, and thesecondary coating 115 may be positioned over the primary coating 114.Proximate to a location where the optical fiber 104 has been splicedtogether, a re-coat coating 116 may be positioned over the glass fiber113 and extend radially outward from the glass fiber 113. The re-coatcoating 116 may form an interface 118 with the primary coating 114 andan interface 119 with the secondary coating 115 in an axial direction sothat the glass fiber 113 is encapsulated by the primary coating 114, thesecondary coating 115 and the re-coat coating 116.

To maintain the structural integrity of the optical fiber 104, thesecondary coating 115 may comprise a wear-resistant material selected tohave a high shear modulus and a high compressive modulus. The primarycoating 114 may be selected to have a low shear modulus and a lowcompressive modulus to provide the optical fiber 104 with flexibility.Because the re-coat coating 116 comprises a single layer, the re-coatcoating 116 may comprise a material selected to have a high shearmodulus and a high compressive modulus to maintain the structuralintegrity of the optical fiber 104 at the location where the opticalfiber 104 has been spliced.

Still referring to FIG. 3, the optical fiber 104 with a re-coat coating116 is depicted under a compressive force 127. Because the primarycoating 114 has a low compressive modulus and the re-coat coating 116has a high compressive modulus, the primary coating 114 elasticallydeforms more than the re-coat coating 116 under the same compressiveforce 127. Because the primary coating 114 elastically deforms more thanthe re-coat coating 116, the optical fiber 104 will deflect more atportions of the optical fiber 104 including primary coating 114 than theoptical fiber 104 deflects at portions of the optical fiber 104including a re-coat coating 116. The difference in the deflection ΔX ofthe optical fiber 104 at portions including a primary coating 114 andportions including a re-coat coating 116 creates stress at the interface118 between the primary coating 114 and the re-coat coating 116. Thestress at the interface 118 between the primary coating 114 and there-coat coating 116 may lead to cohesive failure between the primarycoating 114 and the re-coat coating 116 at the interface 118 exposingthe glass fiber to environmental conditions which may degrade theoptical fiber, the performance of the optical fiber, or even lead tofailure of the optical fiber.

Referring to FIG. 4, an optical fiber 104 is depicted under shearstress, such as the shear stress applied to the optical fiber 104 by thescreen testing apparatus 100 at the first capstan 102. For illustrativepurposes, a series of lines 117 are depicted in the optical fiber 104 toillustrate the strain in the portions of the optical fiber 104. Asdiscussed hereinabove, the first capstan 102 and the second capstan 106may apply a tensile force to the optical fiber 104 during a screen test,and the tensile force may be isolated by impinging the optical fiber 104between the first pinch belt 103 and the first capstan 102. The tensileforce may be applied in a direction generally tangential to the outercircumference 105 of the first capstan 102 (i.e., in the +/− Y directionin the coordinate axis depicted on FIG. 4). Because the primary coating114 of the optical fiber 104 has a low shear modulus and the re-coatcoating 116 has a high shear modulus, the primary coating 114elastically deforms more than the re-coat coating 116 under the sametensile force. Because the primary coating 114 elastically deforms morethan the re-coat coating 116, the optical fiber 104 will deflect more atportions of the optical fiber 104 including the primary coating 114 thanthe optical fiber 104 deflects at portions of the optical fiber 104including only the re-coat coating 116. The difference in the deflectionof the optical fiber 104 at portions including a primary coating 114 andthe deflection at portions including a re-coat coating 116 createsstress at the interface 118 between the primary coating 114 and there-coat coating 116. The stress at the interface 118 between the primarycoating 114 and the re-coat coating 116 may lead to cohesive failurebetween the primary coating 114 and the re-coat coating 116 at theinterface 118.

To reduce the compressive and shear stress placed on the optical fiber104 during the screen testing process, various embodiments of capstanswhich may be used as the first capstan 102 and/or the second capstan 106are described herein. Referring to FIGS. 5A, 5B, and 5C, one embodimentof a capstan 201 is depicted. The capstan 201 is generally cylindrical,and has a diameter DIA1, a width W1, and an outer circumference 105. Theouter circumference 105 of the first capstan 102 includes a fibercontact region 120 extending around the outer circumference 105 of thecapstan 201. The fiber contact region 120 of the capstan 201 may be theportion of the outer circumference 105 of the capstan 201 that engagesthe optical fiber 104 directed over the fiber conveyance pathway 101.The fiber contact region 120 of the capstan 201 has a durometer hardnessof less than or equal to about 40 Shore A. In embodiments, the fibercontact region 120 may have a width W2 that is greater than or equal toabout ten times a diameter of an optical fiber 104 directed over thefiber conveyance pathway 101.

In this embodiment, the fiber contact region 120 may comprise an innerlayer 121. The inner layer 121 of the fiber contact region 120 may bepositioned over the outer circumference 105 of the capstan 201,extending around the outer circumference 105 of the capstan 201. Theinner layer 121 of the fiber contact region 120 has a thickness T1extending radially outward from the outer circumference 105 of thecapstan 201 to an outer circumference 122 of the inner layer 121. Inembodiments, the thickness T1 of the inner layer may be greater than orequal to about 1 mm and less than or equal to about 12 mm. In analternative embodiment, the thickness T1 of the inner layer may begreater than or equal to about 1 mm and less than or equal to about 5mm.

The inner layer 121 of the fiber contact region 120 may be formed from aresilient material. The resilient material of the inner layer 121 may beselected to have a desired hardness and a desired compressive modulusand shear modulus to reduce the compressive and shear stresses on theoptical fiber 104 contacting the fiber contact region 120. Inembodiments, the resilient material of the inner layer 121 is selectedto have a durometer hardness of less than or equal to about 35 Shore A.In another embodiment, the resilient material may be selected to have adurometer hardness of less than or equal to about 20 Shore A.

In embodiments, the resilient material of the inner layer 121 may be anisotropic material, where the durometer hardness of the materialcorrelates to a compressive modulus and a shear modulus of the material.More specifically, a higher durometer hardness value of the resilientmaterial of the inner layer 121 may correlate to a higher compressivemodulus and a higher shear modulus of the resilient material.Conversely, a lower durometer hardness value of the resilient materialof the inner layer 121 may correlate to a lower compressive modulus anda lower shear modulus of the resilient material. As will be described ingreater detail herein, a low durometer hardness value, and consequentlya low compressive modulus and shear modulus of the resilient material ofthe inner layer 121 may reduce the compressive and shear stress in theoptical fiber 104 in contact with the fiber contact region 120.

In embodiments, the resilient material of the inner layer 121 may alsobe selected to have a shear modulus and a compressive modulus of lessthan or equal to about 1 MPa. In another embodiment, the resilientmaterial of the inner layer 121 may be selected to have a shear modulusand a compressive modulus greater than or equal to about 0.1 MPa andless than or equal to about 0.5 MPa. By selecting the resilient materialof the inner layer 121 to have a shear modulus and a compressive modulusof less than or equal to about 1 MPa, the inner layer 121 of the fibercontact region 120 may elastically deform under the compressive forceand tensile force applied by the optical fiber 104. In anotherembodiment, the resilient material of the inner layer 121 may beselected to have the same compressive modulus and shear modulus as theprimary coating 114 of the optical fiber 104 directed over the fiberconveyance pathway 101.

The fiber contact region 120 of the capstan 201 may further include anouter layer 123 positioned over the inner layer 121. In embodiments, theouter layer 123 may extend laterally in a width direction to cover theinner layer 121 of the fiber contact region 120. The outer layer 123 mayhave a thickness T2 extending radially outward from the outercircumference 122 of the inner layer 121 to an outer circumference 124of the outer layer 123. The thickness T2 of the outer layer 123 may begreater than or equal to about 10 μm and less than or equal to about 250μm. In alternative embodiments, the thickness T2 of the outer layer 123may be greater than or equal to about 30 μm and less than or equal toabout 250 μm. In still other embodiments, the thickness T2 of the outerlayer 123 may be greater than or equal to about 10 μm and less than orequal to about 300 μm. In further embodiments, the thickness T2 of theouter layer 123 may be greater than or equal to about 30 μm and lessthan or equal to about 300 μm. In another embodiment, the thickness T2of the outer layer 123 may be greater than or equal to about 10 μm andless than or equal to about 350 μm. In yet another embodiment, thethickness T2 of the outer layer 123 may be greater than or equal toabout 30 μm and less than or equal to about 350 μm.

The outer layer 123 of the fiber contact region 120 may be formed from awear-resistant material. The wear-resistant material of the outer layer123 may be selected to have a desired hardness and a desired compressivemodulus and shear modulus. In one embodiment, the wear-resistantmaterial of the outer layer 123 may be selected to have a durometerhardness greater than or equal to about 55 Shore A and less than orequal to about 90 Shore A. In another embodiment, the wear-resistantmaterial of the outer layer 123 may be selected to have a durometerhardness greater than or equal to about 65 Shore A and less than orequal to about 80 Shore A.

Similar to the resilient material of the inner layer 121, thewear-resistant material of the outer layer 123 may be an isotropicmaterial, where the durometer hardness of the material correlates to acompressive modulus and a shear modulus of the material. Morespecifically, a higher durometer hardness value of the wear-resistantmaterial of the outer layer 123 may correlate to a higher compressivemodulus and a higher shear modulus of the wear-resistant material.Conversely, a lower durometer hardness value of the wear-resistantmaterial of the outer layer 123 may correlate to a lower compressivemodulus and a lower shear modulus of the wear-resistant material. Thewear-resistant material of the outer layer 123 may be selected to have ahigher durometer hardness than the resilient material of the inner layer121, so that the wear-resistant material of the outer layer may reducethe wear on the fiber contact region 120 caused by contact with theoptical fiber 104.

When the fiber contact region 120 includes both an outer layer 123 andan inner layer 121, as depicted in FIGS. 5A-5C, the resilient materialof the inner layer and the wear-resistant material of the outer layer123 may be selected so that the overall durometer hardness of the fibercontact region 120 is less than or equal to about 40 Shore A. Theoverall hardness of the fiber contact region 120 may result as acombination of the durometer hardness and thickness of the inner layer121 and the outer layer 123, and the hardness of the outer circumference105 of the capstan 201. By including an outer layer 123 formed from awear-resistant material, the structural integrity of the fiber contactregion 120 may be maintained, and wear on the inner layer 121 fromcontact with an optical fiber 104 directed over the fiber conveyancepathway 101 may be reduced.

In embodiments, the inner layer 121 and the outer layer 123 may comprisematerials including without limitation, elastomers, thermoplasticpolymers, polyurethane, nylon and the like.

Referring now to FIGS. 6A, 6B, and 6C, another embodiment of the capstan201 is schematically depicted. In this embodiment, the fiber contactregion 120 of the capstan 201 has a durometer hardness of less than orequal to about 40 Shore A, as described above. However, in thisembodiment, the fiber contact region 120 of the capstan 201 includes achannel 125 extending radially inward from the outer circumference 105of the capstan 201. The channel 125 may have a depth d1 extendingradially inward from the outer circumference 105 of the capstan 201, anda width W3 extending across the outer circumference 105 of the capstan201. The depth d1 may be selected to be greater than or equal to 1 mmand less than or equal to 12 mm. In an alternative embodiment, the depthd1 may be selected to be greater than or equal to about 1 mm and lessthan or equal to about 5 mm. The inner layer 121 of the fiber contactregion 120 may be positioned within the channel 125 of the capstan 201.The inner layer 121 may be formed from a resilient material having adurometer hardness of less than or equal to about 35 Shore A, asdescribed above with respect to FIGS. 5A-5C. In another embodiment, theresilient material may be selected to have a durometer hardness of lessthan or equal to about 20 Shore A, as described above with respect toFIGS. 5A-5C. As referenced above with respect to FIGS. 5A-5C, a lowdurometer hardness value of the resilient material of the inner layer121 may reduce the compressive and shear stress in the optical fiber 104in contact with the fiber contact region 120, as will be described ingreater detail herein.

The resilient material of the inner layer 121 may also be selected tohave a shear modulus and a compressive modulus of less than or equal toabout 1 MPa, as described with respect to FIGS. 5A-5C. In anotherembodiment, the resilient material of the inner layer may be selected tohave a shear modulus and a compressive modulus greater than or equal toabout 0.1 MPa and less than or equal to about 0.5 MPa, as describedabove with respect to FIGS. 5A-5C. By selecting the resilient materialof the inner layer 121 to have a shear modulus and a compressive modulusof less than or equal to about 1 MPa, the inner layer 121 of the fibercontact region 120 may elastically deform under the compressive forceand tensile force applied by the optical fiber 104. In anotherembodiment, the resilient material of the inner layer 121 may beselected to have the same compressive modulus and shear modulus as theprimary coating 114 of the optical fiber 104 directed over the fiberconveyance pathway 101, as described with respect to FIGS. 5A-5C.

In one embodiment, a vacuum suction may be applied to the channel 125 toretain the inner layer 121 within the channel 125. The vacuum suctionmay be applied to the channel 125 by mechanisms including, withoutlimitation, a one-way valve positioned on the capstan 201, the one-wayvalve in fluid communication with the channel 125. As the capstan 201rotates, the vacuum suction may counteract a centrifugal force to retainthe inner layer 121 within the channel 125. By positioning the innerlayer 121 within a channel 125 and utilizing a force, such as a vacuumsuction, to retain the inner layer 121 within the channel 125, the innerlayer 121 may be prevented from coming free of the fiber contact region120 because of a centrifugal force cause by the rotation of the capstan201.

The fiber contact region 120 may optionally include an outer layer 123.The outer layer 123 of the fiber contact region 120 may be positionedover the inner layer 121 of the fiber contact region 120 such that theouter layer 123 encloses the channel 125 of the capstan 201. The outerlayer 123 may be formed from a wear-resistant material having adurometer hardness of greater than or equal to about 55 Shore A and lessthan or equal to about 90 Shore A, as described above with respect toFIGS. 5A-5C. In another embodiment, the outer layer 123 may be selectedto have a durometer hardness greater than or equal to about 65 Shore Aand less than or equal to about 80 Shore A, as described above withrespect to FIGS. 5A-5C. As described above with respect to FIGS. 5A-5C,by including an outer layer 123 formed from a wear-resistant material,the structural integrity of the fiber contact region 120 may bemaintained, and wear on the inner layer 121 from contact with an opticalfiber directed over the fiber conveyance pathway may be reduced.

When the fiber contact region 120 includes both an outer layer 123 andan inner layer 121, as described above with respect to FIGS. 5A-5C, theresilient material of the inner layer and the wear-resistant material ofthe outer layer 123 may be selected so that the overall durometerhardness of the fiber contact region 120 is less than or equal to about40 Shore A. By including an outer layer 123 formed from a wear-resistantmaterial, the structural integrity of the fiber contact region 120 maybe maintained, and wear on the inner layer 121 from contact with anoptical fiber 104 directed over the fiber conveyance pathway 101 may bereduced.

Referring now to FIGS. 7A, 7B, and 7C, another embodiment of the capstan201 is schematically depicted. The fiber contact region 120 of thecapstan 201 has a durometer hardness of less than or equal to about 40Shore A, as described above. However, in this embodiment, the fibercontact region 120 of the capstan 201 includes a channel 125 extendingradially inward from the outer circumference 105 of the capstan 201. Thechannel 125 has a width W4 at a position proximate to the outercircumference 105 of the capstan 201, and a width W5 at a positionradially inward from the outer circumference 105 of the capstan 201. Thechannel 125 may be tapered, such that the width W4 of the channel 125 atthe outer circumference 105 is less than the width W5 is at a positionof the channel 125 radially inward from the outer circumference 105 ofthe capstan 201. The inner layer 121 of the fiber contact region 120 maybe positioned within the channel 125 of the capstan 201. The inner layer121 may be formed from a resilient material having a durometer hardnessof less than or equal to about 35 Shore A, as described above withrespect to FIGS. 5A-5C. In another embodiment, the resilient materialmay be selected to have a durometer hardness of less than or equal toabout 20 Shore A, as described above with respect to FIGS. 5A-5C. Asreferenced above with respect to FIGS. 5A-5C, a low durometer hardnessvalue of the resilient material of the inner layer 121 may reduce thecompressive and shear stress in the optical fiber 104 in contact withthe fiber contact region 120, as will be described in greater detailherein.

The resilient material of the inner layer 121 may also be selected tohave a shear modulus and a compressive modulus of less than or equal toabout 1 MPa, as described with respect to FIGS. 5A-5C. In anotherembodiment, the resilient material of the inner layer may be selected tohave a shear modulus and a compressive modulus greater than or equal toabout 0.1 MPa and less than or equal to about 0.5 MPa, as describedabove with respect to FIGS. 5A-5C. By selecting the resilient materialof the inner layer 121 to have a shear modulus and a compressive modulusof less than or equal to about 1 MPa, the inner layer 121 of the fibercontact region 120 may elastically deform under the compressive forceand tensile force applied by the optical fiber 104. In anotherembodiment, the resilient material of the inner layer 121 may beselected to have the same compressive modulus and shear modulus as theprimary coating 114 of the optical fiber 104 directed over the fiberconveyance pathway 101, as described with respect to FIGS. 5A-5C.

By tapering the width of the channel 125, the shape of the channel 125may prevent a centrifugal force caused by the rotation of the capstan201 from causing the inner layer 121 to come free from the channel 125of the capstan 201.

The fiber contact region 120 may optionally include an outer layer 123positioned over the inner layer 121 of the fiber contact region 120 suchthat the outer layer 123 encloses the channel 125 of the capstan 201, asdescribed with respect to FIGS. 6A-6C. The outer layer 123 may be formedfrom a wear-resistant material having a durometer hardness of greaterthan or equal to about 55 Shore A and less than or equal to about 90Shore A, as described above with respect to FIGS. 5A-5C. In anotherembodiment, the outer layer 123 may be selected to have a durometerhardness greater than or equal to about 65 Shore A and less than orequal to about 80 Shore A, as described above with respect to FIGS.5A-5C. As described above with respect to FIGS. 5A-5C, by including anouter layer 123 formed from a wear-resistant material, the structuralintegrity of the fiber contact region 120 may be maintained, and wear onthe inner layer 121 from contact with an optical fiber directed over thefiber conveyance pathway may be reduced.

When the fiber contact region 120 includes both an outer layer 123 andan inner layer 121, as described above with respect to FIGS. 5A-5C, theresilient material of the inner layer and the wear-resistant material ofthe outer layer 123 may be selected so that the overall durometerhardness of the fiber contact region 120 is less than or equal to about40 Shore A. By including an outer layer 123 formed from a wear-resistantmaterial, the structural integrity of the fiber contact region 120 maybe maintained, and wear on the inner layer 121 from contact with anoptical fiber 104 directed over the fiber conveyance pathway 101 may bereduced.

Referring now to FIGS. 8A, 8B, and 8C, another embodiment of the capstan201 is schematically depicted. The fiber contact region 120 of thecapstan 201 has a durometer hardness of less than or equal to about 40Shore A, as described above. However, in this embodiment, the fibercontact region 120 of the capstan 201 includes a channel 125 extendingradially inward from the outer circumference 105 of the capstan 201. Thechannel 125 may have a depth d1 extending radially inward from the outercircumference 105 of the capstan 201, and a width W2 extending acrossthe outer circumference 105 of the capstan 201. The inner layer 121 ofthe fiber contact region 120 may be positioned within the channel 125 ofthe capstan 201. The inner layer 121 may be formed from a resilientmaterial having a durometer hardness of less than or equal to about 35Shore A, as described above with respect to FIGS. 5A-5C. In anotherembodiment, the resilient material may be selected to have a durometerhardness of less than or equal to about 20 Shore A, as described abovewith respect to FIGS. 5A-5C. As referenced above with respect to FIGS.5A-5C, a low durometer hardness value of the resilient material of theinner layer 121 may reduce the compressive and shear stress in theoptical fiber 104 in contact with the fiber contact region 120, as willbe described in greater detail herein.

The resilient material of the inner layer 121 may also be selected tohave a shear modulus and a compressive modulus of less than or equal toabout 1 MPa, as described with respect to FIGS. 5A-5C. In anotherembodiment, the resilient material of the inner layer may be selected tohave a shear modulus and a compressive modulus greater than or equal toabout 0.1 MPa and less than or equal to about 0.5 MPa, as describedabove with respect to FIGS. 5A-5C. By selecting the resilient materialof the inner layer 121 to have a shear modulus and a compressive modulusof less than or equal to about 1 MPa, the inner layer 121 of the fibercontact region 120 may elastically deform under the compressive forceand tensile force applied by the optical fiber 104. In anotherembodiment, the resilient material of the inner layer 121 may beselected to have the same compressive modulus and shear modulus as theprimary coating 114 of the optical fiber 104 directed over the fiberconveyance pathway 101, as described with respect to FIGS. 5A-5C.

At least one fastener 126 is positioned through the channel 125 and theinner layer 121 of the capstan 201. The at least one fastener mayprevent a centrifugal force caused by the rotation of the capstan 201from causing the inner layer 121 to come free from the channel 125 ofthe capstan 201. The fastener 126 may include, without limitation, abolt, a screw, a pin or the like.

The fiber contact region 120 may optionally include an outer layer 123positioned over the inner layer 121 of the fiber contact region 120 suchthat the outer layer 123 encloses the channel 125 of the capstan 201, asdescribed with respect to FIGS. 6A-6C. The outer layer 123 of the fibercontact region 120 may be positioned over the inner layer 121 of thefiber contact region 120 such that the outer layer 123 encloses thechannel 125 of the capstan 201. The outer layer 123 may be formed from awear-resistant material having a durometer hardness of greater than orequal to about 55 Shore A and less than or equal to about 90 Shore A, asdescribed above with respect to FIGS. 5A-5C. In another embodiment, theouter layer 123 may be selected to have a durometer hardness greaterthan or equal to about 65 Shore A and less than or equal to about 80Shore A, as described above with respect to FIGS. 5A-5C. As describedabove with respect to FIGS. 5A-5C, by including an outer layer 123formed from a wear-resistant material, the structural integrity of thefiber contact region 120 may be maintained, and wear on the inner layer121 from contact with an optical fiber directed over the fiberconveyance pathway may be reduced.

When the fiber contact region 120 includes both an outer layer 123 andan inner layer 121, as described above with respect to FIGS. 5A-5C, theresilient material of the inner layer and the wear-resistant material ofthe outer layer 123 may be selected so that the overall durometerhardness of the fiber contact region 120 is less than or equal to about40 Shore A. By including an outer layer 123 formed from a wear-resistantmaterial, the structural integrity of the fiber contact region 120 maybe maintained, and wear on the inner layer 121 from contact with anoptical fiber 104 directed over the fiber conveyance pathway 101 may bereduced.

Referring now to FIGS. 9A, 9B, 9C, and 9D another embodiment of thecapstan 201 is schematically depicted. In this embodiment, the fibercontact region 120 of the capstan 201 has a durometer hardness of lessthan or equal to about 40 Shore A, as described above. However, in thisembodiment, the fiber contact region 120 of the capstan 201 includes achannel 125 extending radially inward from the outer circumference 105of the capstan 201, and the capstan includes at least one cog 129positioned within the channel 125. The channel 125 may have a depth d1extending radially inward from the outer circumference 105 of thecapstan 201, and a width W3 extending across the outer circumference 105of the capstan 201, as described with respect to FIGS. 6A-6C. The depthd1 may be selected to be greater than or equal to 1 mm and less than orequal to 12 mm. In an alternative embodiment, the depth d1 may beselected to be greater than or equal to about 1 mm and less than orequal to about 5 mm, as described with respect to FIGS. 6A-6C. The innerlayer 121 of the fiber contact region 120 may be positioned within thechannel 125 of the capstan 201. The inner layer 121 may be formed from aresilient material having a durometer hardness of less than or equal toabout 35 Shore A, as described above with respect to FIGS. 5A-5C. Inanother embodiment, the resilient material may be selected to have adurometer hardness of less than or equal to about 20 Shore A, asdescribed above with respect to FIGS. 5A-5C. As referenced above withrespect to FIGS. 5A-5C, a low durometer hardness value of the resilientmaterial of the inner layer 121 may reduce the compressive and shearstress in the optical fiber 104 in contact with the fiber contact region120, as will be described in greater detail herein.

The resilient material of the inner layer 121 may also be selected tohave a shear modulus and a compressive modulus of less than or equal toabout 1 MPa, as described with respect to FIGS. 5A-5C. In anotherembodiment, the resilient material of the inner layer may be selected tohave a shear modulus and a compressive modulus greater than or equal toabout 0.1 MPa and less than or equal to about 0.5 MPa, as describedabove with respect to FIGS. 5A-5C. By selecting the resilient materialof the inner layer 121 to have a shear modulus and a compressive modulusof less than or equal to about 1 MPa, the inner layer 121 of the fibercontact region 120 may elastically deform under the compressive forceand tensile force applied by the optical fiber 104. In anotherembodiment, the resilient material of the inner layer 121 may beselected to have the same compressive modulus and shear modulus as theprimary coating 114 of the optical fiber 104 directed over the fiberconveyance pathway 101, as described with respect to FIGS. 5A-5C.

The capstan 201 includes at least one cog 129 positioned within thechannel 125. The at least one cog 129 is positioned within the channel125, extending radially outward toward the outer circumference 105 ofthe capstan 201 and engaging the inner layer 121. By engaging the innerlayer 121, the at least one cog 129 may retain the position of the innerlayer 121, preventing the inner layer from rotating with respect to thecapstan 201 when the fiber contact region 120 contacts an optical fiber.

In one embodiment, a vacuum suction may be applied to the channel 125 toretain the inner layer 121 within the channel 125, as described abovewith respect to FIGS. 6A-6C. The vacuum suction may be applied to thechannel 125 by mechanisms including, without limitation, a one-way valvepositioned on the capstan 201, the one-way valve in fluid communicationwith the channel 125. As the capstan 201 rotates, the vacuum suction maycounteract a centrifugal force to retain the inner layer 121 within thechannel 125. By positioning the inner layer 121 within a channel 125 andutilizing a force, such as a vacuum suction, to retain the inner layer121 within the channel 125, the inner layer 121 may be prevented fromcoming free of the fiber contact region 120 because of a centrifugalforce cause by the rotation of the capstan 201.

The fiber contact region 120 may optionally include an outer layer 123.The outer layer 123 of the fiber contact region 120 may be positionedover the inner layer 121 of the fiber contact region 120 such that theouter layer 123 encloses the channel 125 of the capstan 201. The outerlayer 123 may be formed from a wear-resistant material having adurometer hardness of greater than or equal to about 55 Shore A and lessthan or equal to about 90 Shore A, as described above with respect toFIGS. 5A-5C. In another embodiment, the outer layer 123 may be selectedto have a durometer hardness greater than or equal to about 65 Shore Aand less than or equal to about 80 Shore A, as described above withrespect to FIGS. 5A-5C. As described above with respect to FIGS. 5A-5C,by including an outer layer 123 formed from a wear-resistant material,the structural integrity of the fiber contact region 120 may bemaintained, and wear on the inner layer 121 from contact with an opticalfiber directed over the fiber conveyance pathway may be reduced.

When the fiber contact region 120 includes both an outer layer 123 andan inner layer 121, as described above with respect to FIGS. 5A-5C, theresilient material of the inner layer and the wear-resistant material ofthe outer layer 123 may be selected so that the overall durometerhardness of the fiber contact region 120 is less than or equal to about40 Shore A. By including an outer layer 123 formed from a wear-resistantmaterial, the structural integrity of the fiber contact region 120 maybe maintained, and wear on the inner layer 121 from contact with anoptical fiber 104 directed over the fiber conveyance pathway 101 may bereduced.

Referring now to FIGS. 10A, 10B, 10C, and 10D another embodiment of thecapstan 201 is schematically depicted. The fiber contact region 120 ofthe capstan 201 has a durometer hardness of less than or equal to about40 Shore A, as described above. However, in this embodiment, the fibercontact region 120 of the capstan 201 includes a channel 125 extendingradially inward from the outer circumference 105 of the capstan 201, andthe capstan 201 includes at least one cog 129 positioned within thechannel 125. The channel 125 has a width W4 at a position proximate tothe outer circumference 105 of the capstan 201, and a width W5 at aposition radially inward from the outer circumference 105 of the capstan201, as described with respect to FIGS. 7A-7C. The channel 125 may betapered, such that the width W4 of the channel 125 at the outercircumference 105 is less than the width W5 is at a position of thechannel 125 radially inward from the outer circumference 105 of thecapstan 201, as described with respect to FIGS. 7A-7C. The inner layer121 of the fiber contact region 120 may be positioned within the channel125 of the capstan 201. The inner layer 121 may be formed from aresilient material having a durometer hardness of less than or equal toabout 35 Shore A, as described above with respect to FIGS. 5A-5C. Inanother embodiment, the resilient material may be selected to have adurometer hardness of less than or equal to about 20 Shore A, asdescribed above with respect to FIGS. 5A-5C. As referenced above withrespect to FIGS. 5A-5C, a low durometer hardness value of the resilientmaterial of the inner layer 121 may reduce the compressive and shearstress in the optical fiber 104 in contact with the fiber contact region120, as will be described in greater detail herein.

The resilient material of the inner layer 121 may also be selected tohave a shear modulus and a compressive modulus of less than or equal toabout 1 MPa, as described with respect to FIGS. 5A-5C. In anotherembodiment, the resilient material of the inner layer may be selected tohave a shear modulus and a compressive modulus greater than or equal toabout 0.1 MPa and less than or equal to about 0.5 MPa, as describedabove with respect to FIGS. 5A-5C. By selecting the resilient materialof the inner layer 121 to have a shear modulus and a compressive modulusof less than or equal to about 1 MPa, the inner layer 121 of the fibercontact region 120 may elastically deform under the compressive forceand tensile force applied by the optical fiber 104. In anotherembodiment, the resilient material of the inner layer 121 may beselected to have the same compressive modulus and shear modulus as theprimary coating 114 of the optical fiber 104 directed over the fiberconveyance pathway 101, as described with respect to FIGS. 5A-5C.

By tapering the width of the channel 125, the shape of the channel 125may prevent a centrifugal force caused by the rotation of the capstan201 from causing the inner layer 121 to come free from the channel 125of the capstan 201.

The capstan 201 includes at least one cog 129 positioned within thechannel 125, as described above with respect to FIGS. 9A-9D. The atleast one cog 129 is positioned within the channel 125, extendingradially outward toward the outer circumference 105 of the capstan 201and engaging the inner layer 121, as described above with respect toFIGS. 9A-9D. By engaging the inner layer 121, the at least one cog 129may retain the position of the inner layer 121, preventing the innerlayer from rotating with respect to the capstan 201 when the fibercontact region 120 contacts an optical fiber.

The fiber contact region 120 may optionally include an outer layer 123positioned over the inner layer 121 of the fiber contact region 120 suchthat the outer layer 123 encloses the channel 125 of the capstan 201, asdescribed with respect to FIGS. 6A-6C. The outer layer 123 may be formedfrom a wear-resistant material having a durometer hardness of greaterthan or equal to about 55 Shore A and less than or equal to about 90Shore A, as described above with respect to FIGS. 5A-5C. In anotherembodiment, the outer layer 123 may be selected to have a durometerhardness greater than or equal to about 65 Shore A and less than orequal to about 80 Shore A, as described above with respect to FIGS.5A-5C. As described above with respect to FIGS. 5A-5C, by including anouter layer 123 formed from a wear-resistant material, the structuralintegrity of the fiber contact region 120 may be maintained, and wear onthe inner layer 121 from contact with an optical fiber directed over thefiber conveyance pathway may be reduced.

When the fiber contact region 120 includes both an outer layer 123 andan inner layer 121, as described above with respect to FIGS. 5A-5C, theresilient material of the inner layer and the wear-resistant material ofthe outer layer 123 may be selected so that the overall durometerhardness of the fiber contact region 120 is less than or equal to about40 Shore A. By including an outer layer 123 formed from a wear-resistantmaterial, the structural integrity of the fiber contact region 120 maybe maintained, and wear on the inner layer 121 from contact with anoptical fiber 104 directed over the fiber conveyance pathway 101 may bereduced.

Referring now to FIGS. 11A, 11B, and 11C, another embodiment of thecapstan 201 is schematically depicted. In this embodiment, the fibercontact region 120 of the capstan 201 has a durometer hardness of lessthan or equal to about 40 Shore A, as described above. However, in thisembodiment, the fiber contact region 120 of the capstan 201 includes abase layer 130 positioned on the outer circumference 122 of the capstan201.

In embodiments, the base layer 130 is positioned over the outercircumference 122 of the capstan 201. The inner layer 121 is positionedover and bonded to the base layer 130. To bond the inner layer 121 tothe base layer 130, the inner layer 121 and the base layer 130 may bedirectly bonded to one another, or the inner layer 121 and the baselayer 130 may be fastened by an adhesive or the like. The base layer 130has a thickness T3 extending radially outward from the outercircumference 122 of the capstan 201 to the inner layer 121. Inembodiments, the thickness T3 of the base layer 130 may be greater thanor equal to about 0.5 mm and less than or equal to about 2.0 mm. Inanother embodiment, the thickness T3 of the base layer 130 may begreater than or equal to about 0.5 mm and less than or equal to about1.0 mm.

In embodiments, the base layer 130 may be formed from an inflexiblematerial. The inflexible material of the base layer 130 may be selectedto have a desired hardness and a desired compressive and shear modulusto counteract a centrifugal force acting on the base layer 130 and theinner layer 121. In embodiments, the inflexible material of the baselayer 130 is selected to have a hardness less than or equal to about 90Shore A. In another embodiment, the inflexible material of the baselayer 130 is selected to have a hardness less than or equal to about 53Shore D.

Similar to the inner layer 121 as described above with respect to FIGS.5A-5C, the inflexible material of the base layer 130 may be an isotropicmaterial, where the durometer hardness of the material correlates to acompressive modulus and a shear modulus of the material. Morespecifically, a higher durometer hardness value of the inflexiblematerial of the inner layer 130 may correlate to a higher compressivemodulus and a higher shear modulus. Conversely, a lower durometerhardness value of the inflexible material of the base layer 130 maycorrelate to a lower compressive modulus and shear modulus. As will bedescribed in greater detail herein, a relatively high durometer hardnessvalue, and consequently a high compressive and shear modulus of theinflexible material may assist in resisting centrifugal force acting onthe base layer 130 and the inner layer 121 bonded to the base layer 130.

In embodiments, the inflexible material of the base layer 130 may beselected to have a shear modulus and a compressive modulus of less thanor equal to about 150 MPa. In another embodiment, the inflexiblematerial of the base layer 130 may be selected to have a shear andcompressive modulus less than or equal to about 145 MPa. By selectingthe inflexible material of the base layer 130 to have a durometerhardness of less than or equal to about 150 MPa, the base layer 130 mayresist plastic deformation resulting from a centrifugal force applied tothe base layer 130 as a result of the rotation of the capstan 201.

In embodiments, the base layer 130 may comprise materials includingwithout limitation, elastomers, thermoplastic polymers, polyurethane,nylon and the like.

The inner layer 121 may be formed from a resilient material having adurometer hardness of less than or equal to about 35 Shore A, asdescribed above with respect to FIGS. 5A-5C. In another embodiment, theresilient material may be selected to have a durometer hardness of lessthan or equal to about 20 Shore A, as described above with respect toFIGS. 5A-5C. As referenced above with respect to FIGS. 5A-5C, a lowdurometer hardness value of the resilient material of the inner layer121 may reduce the compressive and shear stress in the optical fiber 104in contact with the fiber contact region 120, as will be described ingreater detail herein.

The resilient material of the inner layer 121 may also be selected tohave a shear modulus and a compressive modulus of less than or equal toabout 1 MPa, as described with respect to FIGS. 5A-5C. In anotherembodiment, the resilient material of the inner layer may be selected tohave a shear modulus and a compressive modulus greater than or equal toabout 0.1 MPa and less than or equal to about 0.5 MPa, as describedabove with respect to FIGS. 5A-5C. By selecting the resilient materialof the inner layer 121 to have a shear modulus and a compressive modulusof less than or equal to about 1 MPa, the inner layer 121 of the fibercontact region 120 may elastically deform under the compressive forceand tensile force applied by the optical fiber 104. In anotherembodiment, the resilient material of the inner layer 121 may beselected to have the same compressive modulus and shear modulus as theprimary coating 114 of the optical fiber 104 directed over the fiberconveyance pathway 101, as described with respect to FIGS. 5A-5C.

The fiber contact region 120 may optionally include an outer layer 123.The outer layer 123 of the fiber contact region 120 may be positionedover the inner layer 121 of the fiber contact region 120 such that theouter layer 123 encloses the channel 125 of the capstan 201. The outerlayer 123 may be formed from a wear-resistant material having adurometer hardness of greater than or equal to about 55 Shore A and lessthan or equal to about 90 Shore A, as described above with respect toFIGS. 5A-5C. In another embodiment, the outer layer 123 may be selectedto have a durometer hardness greater than or equal to about 65 Shore Aand less than or equal to about 80 Shore A, as described above withrespect to FIGS. 5A-5C. As described above with respect to FIGS. 5A-5C,by including an outer layer 123 formed from a wear-resistant material,the structural integrity of the fiber contact region 120 may bemaintained, and wear on the inner layer 121 from contact with an opticalfiber directed over the fiber conveyance pathway may be reduced.

When the fiber contact region 120 includes an outer layer 123, an innerlayer 121, and a base layer 130, the resilient material of the innerlayer, the wear-resistant material of the outer layer 123, and thematerial of the base layer 130 may be selected so that the overalldurometer hardness of the fiber contact region 120 is less than or equalto about 40 Shore A. By including an outer layer 123 formed from awear-resistant material, the structural integrity of the fiber contactregion 120 may be maintained, and wear on the inner layer 121 fromcontact with an optical fiber 104 directed over the fiber conveyancepathway 101 may be reduced. By including a base layer 130 formed from aninflexible material which is bonded to the resilient material of theinner layer 121, the base layer 130 may resist a centrifugal forceacting on the base layer 130 and the inner layer 121. By resisting thecentrifugal force, the base layer 130 may assist in retaining theposition of the inner layer 121 on the capstan 201.

Referring to FIG. 12, another embodiment of the capstan 201 is depicted.The fiber contact region 120 of the capstan 201 has a durometer hardnessof less than or equal to about 40 Shore A, as described above. However,in this embodiment, the capstan 201 includes a channel 125 extendingradially inward from the outer circumference 105 of the capstan 201. Thechannel 125 may have a depth d1 extending radially inward from the outercircumference 105 of the capstan 201, and a width W2 extending acrossthe outer circumference 105 of the capstan 201. The width W2 may begreater than or equal to about ten times a diameter of an optical fiber104 directed over the fiber conveyance pathway 101, as described withrespect to FIGS. 5A-5C. An outer layer 123 of the fiber contact region120 may be positioned over the channel 125, enclosing the channel 125 toform an enclosed chamber. However, in this embodiment, an inner layer121 is not positioned in the channel 125, and the channel 125 isunfilled.

The outer layer 123 may be formed from a wear-resistant material havinga durometer hardness of greater than or equal to about 55 Shore A andless than or equal to about 90 Shore A, as described above with respectto FIGS. 5A-5C.

In this embodiment, a pressure may be applied within the channel 125 sothat the pressure is exerted against the outer layer 123 such that thefiber contact region exhibits a durometer hardness of less than about 40Shore A. The pressure may be applied within the channel by mechanismsincluding, without limitation, a one-way valve positioned on the capstan201, the one-way valve in fluid communication with the channel 125.

While specific reference has been made herein to embodiments of thecapstan 201 of the screen testing apparatus 100, it should be understoodthat the first capstan 102 and the second capstan 106 of the screentesting apparatus may be similarly configured to include a fiber contactregion 120 according to the embodiments described herein.

As described and depicted hereinabove, various embodiments of the fibercontact region 120 of the capstan 201 to reduce the compressive andshear stress placed on the optical fiber 104 during the screen testingprocess are disclosed. Referring to FIG. 13, a cross section of anoptical fiber 104 directed over a capstan including a fiber contactregion 120 according to one or more or the embodiments described hereinis schematically depicted. The optical fiber 104 is depicted under acompressive force 127, such as the compressive force applied to theoptical fiber 104 by the first pinch belt 103 as the first pinch belt103 impinges the optical fiber 104 against the fiber contact region 120of the capstan 201. The fiber contact region 120 elastically deforms adistance ΔX2 under the compressive force applied to the optical fiber104, allowing the high modulus re-coat coating 116 of the optical fiberto depress into the fiber contact region 120. Because the fiber contactregion 120 elastically deforms under the compressive force applied tothe optical fiber 104, the difference in the amount of deflection ΔX1between the portion of the optical fiber 104 including a re-coat coating116 and the portion of the optical fiber 104 including a primary coating114 is reduced. Because the difference in the amount of deflection isreduced, the stress at the interface 118 between the primary coating 114and the re-coat coating 116 is reduced, which may decrease thelikelihood of cohesive failure between the primary coating 114 and there-coat coating 116 at the interface 118.

Referring to FIG. 14, an optical fiber is schematically depicted undershear stress, such as the shear stress applied to the optical fiber 104by the screen testing apparatus 100 at the capstan 201, with the capstan201 including a fiber contact region 120 according to one or more or theembodiments described herein. The fiber contact region 120 elasticallydeforms under the shear force applied to the optical fiber 104, reducingthe elastic deformation in the primary coating 114 of the optical fiber104. Because the elastic deformation in the primary coating 114 of theoptical fiber 104 is reduced, the difference in the amount of deflectionbetween the portion of the optical fiber 104 including a re-coat coating116 and the portion of the optical fiber 104 including a primary coating114 is reduced. As the difference in the amount of deflection isreduced, the stress, and accordingly the strain illustrated by lines 117at the interface 118 between the primary coating 114 and the re-coatcoating 116 is reduced. Because the stress at the interface 118 betweenthe primary coating 114 and the re-coat coating 116 is reduced, thelikelihood of cohesive failure between the primary coating 114 and there-coat coating 116 at the interface 118 may decrease.

Accordingly, by including a capstan with a fiber contact region having adesired hardness and compressive and shear modulus, the stress impartedon the coatings of an optical fiber during a screen test process may bereduced. Further, by including a wear-resistant outer layer over aresilient inner layer, the stress imparted on the coatings of theoptical fiber may be reduced, while the wear on the fiber contact regionfrom contact with the optical fiber may be minimized.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments describedherein without departing from the spirit and scope of the claimedsubject matter. Thus it is intended that the specification cover themodifications and variations of the various embodiments described hereinprovided such modification and variations come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method for screen testing an optical fiber, themethod comprising: drawing optical fiber on a fiber conveyance pathway;directing the optical fiber around a capstan, the capstan having anouter circumference and a fiber contact region extending around theouter circumference, the fiber contact region comprising: an inner layerof resilient material positioned on the outer circumference of thecapstan; an outer layer of wear-resistant material positioned over theinner layer of resilient material, the outer layer of wear-resistantmaterial having a durometer hardness of less than or equal to 90 ShoreA, wherein the fiber contact region has a durometer hardness of lessthan or equal to 40 Shore A; and impinging the optical fiber between apinch belt positioned adjacent to the fiber conveyance pathway and thefiber contact region of the capstan, wherein the fiber contact regionelastically deforms and the optical fiber is depressed into the fibercontact region of the capstan as the optical fiber is impinged.